Photodissociation studies of M(furan)(+) (M = Cu, Ag, and Au) and Au(C3H4)(+) complexes

The group 11 metal/furan cationic complexes were generated using a laser va porization technique combined with a supersonic beam expansion in a time-of -flight mass spectrometer. From the viewpoint of the ionization energies, t hese complexes were treated as Cu+-furan, Ag+-furan, and Au-furan(+). The p hotodissociative ligand-to-metal charge transfer with an exclusive furan ca tion was observed for Cu and Ag, whereas a simple bond cleavage with furan( +) formation was inspected for Au. The photofragment spectra were recorded as a function of the laser wavelength. The continuous and structureless ban ds were measured in each complex. The thresholds of the fragment appearance determined the upper limits of the ground-state binding energy with 37 kca l/mol for Cu+-furan, 28 kcal/mol for Ag+-furan, and 62 kcal/mol for Au-fura n(+). An ab initio approach at the MP2 level was employed to optimize the g eometries of the furan complexes and the binding energies were obtained usi ng CCSD(T) single point calculations. The measured binding energies in both Cu and Ag complexes approximate to the theoretical predictions. Both the e xperimental and theoretical measurements yielded the enhanced bond strength for Au complex. In addition, a fu,ran ring opening process leading to Au+- C3H4 production was observed in the reactions of a gold atom with a furan m olecule. The binding energy was taken as a reference to discern three possi ble isomers, i.e., allene, cyclopropene, and propyne, as C3H4 species by me ans of experimental and theoretical approaches.